Question

On a certain multiple-choice test, you receive 7 marks for every question you get right, but lose 3 marks for every question you get wrong. Petunia answered all 130 questions on the test but received only 530 marks. How many questions did she answer correctly?

Answer 1

Given:

Petunia answered all 130 questions on the test but received only 530 marks.

To find:

Number of the questions answered correctly.

Solution:

1) 7 Marks are offered for every right question. So if all the questions were correct then the marks would be 910.

2) 3 marks are deducted for every wrong questions. So if all the questions were wrong then the marks would be -390

3) By the concept of the mixture allegation,

Right             :                Wrong

910                                  -390

                   530

920                                  380

• Right:Wrong = 92:38

4) Number of right questions are 92 and wrong questions are 38.

Number of the questions answered correctly are 92.